Corrosive effects which occur due to electrolytic action when two dissimilar metals are immersed in an electrolyte such as seawater, are well known. Such corrosive effects have been noted, for example, in ships and in parts of marine propulsion systems used in saltwater.
Examples of prior art patents relating to electrolytic action and to various means for reducing the corrosive effects of electrolysis in saltwater include the Warner U.S. Pat. No., 3,330,751, issued July 11, 1967; the Gruber U.S. Pat. No. 3,169,504, issued Feb. 16, 1965; the Harms et al. U.S. Pat. No. 4,196,064, issued Apr. 1, 1980; and the Byrd U.S. Pat. No. 3,240,180, issued Mar. 15, 1966.
Attention is also directed to the Metcalf U.S. Pat. No. 4,236,872, issued Apr. 8, 1975, which illustrates the construction of the lower units of prior art marine propulsion devices.